Portable electronic devices have become dominant in various segments of the economy outside of the consumer segment. For example, over the last two decades portable electronic devices have come to include not only calculators, general processing computer systems, cellular telephones, and personal digital assistants, but also portable electronic devices in the commercial segment, such as, bar code scanners, point of sale terminal, electronic toll reader and the like. The introduction of wireless standards, such as BLUETOOTH® wireless Fidelity and the 802.11e standard has increased the portability of devices by facilitating the independence of the same from traditional wiring and power infrastructures. In short, a large percentage of portable electronic devices are now battery powered with the percentage seen as increasing in the foreseeable future. To increase the operational efficiency of these portable devices, power management has become increasingly important.
Power management is traditionally exercised by terminating power to a device or reducing the power consumed by a device through terminating power to various sub-systems of the same. An early example of power management is the Advanced Power Management (APM) standard that reduces power consumed by a computer system through terminating operation of a subset of the subsystems and reducing operational performance of other subsystems. APM allows a basic integrated operating system (BIOS) of a general purpose computing system to regulate power management. This may be achieved by reducing the operational speed of the CPU speed, terminating operation of hard disk drives, terminating power to a monitor. The power reduction may be implemented after a preset period of inactivity.
The APM standard was replaced by Advanced Configuration and Power Interface (ACPI) which permits the operating system of a general purpose computing system to regulate power management. The (ACPI) supports keys on a normal keyboard for suspending or powering off the computer and has been extended to support Power management keys, e.g., keys on a keyboard dedicated to implementing specific power management functions such as gating power, placing the computer system in a low power (sleep) mode and returning the computer system to operational mode from the sleep mode (wake).
A need exists, therefore, to provide improved techniques for power management of portable devices.